Sound-absorbing panel for air-conditioning ducts and the like

ABSTRACT

A panel for the guidance of an air flow comprises a body of sheet material provided on opposite sides with mutually offset nozzles in the form of hollow bosses or perforated ribs converging outwardly. The nozzles are formed by alternately bending the sheet material in opposite directions whereby a protuberance on one side corresponds to a depression on the other.

United States Patent [191 Morresi et a1.

1 1 SOUND-ABSORBING PANEL FOR AlR-CQNDITIONING DUCTS AND THE LIKE [76]Inventors: Nello Morresi, Via B. Cellini, 3,

Milan; Egidio Villa, Via Ampero. 49, Milan, both of Italy [22] Filed:Jan. 10, 1972 [21] Appl. No.: 216,547

[30] Foreign Application Priority Data Jan. 11,1971 ltaly ..'192l5/7l[52] US. Cl 181/33 G, 161/110, 161/133 [51] Int. Cl E04b 1/84, B32b 3/10[58] Field of Search 181/33 R, 33 G, 33 GA, 181/35 R; Dl8/2 B; 52/144,145; 161/68,

[ 56] References Cited UNITED STATES PATENTS Coffman 181/33 0 June 4,1974 3,103,255 9/1963 1305011161111. 181/336 3,227,598 1/1966 Robb161/127 X 3,479,779 11/1969 Ziegler... 52/144 3,525.663 8/1970 H1110161/68 3,597,891 8/1971 Martin.... 52/145 3,663,346 5/1972 SChOLll161/611 FOREIGN PATENTS OR APPLICATlONS 1,121,259 4/1956 France 131/33 GPrimary Examiner-'Richard B. Wilkinson Assistant Examiner.1ohn F.Gonzales Attorney, Agent, or FirmKarl E. Ross; Herbert Dubno [57]ABSTRACT A panel for the guidance of an air flow comprises a body ofsheet material provided on opposite sides with mutually offset nozzlesin the form of hollow bosses or perforated ribs converging outwardly.The nozzles are formed by alternately bending the sheet material inopposite directions whereby a protuberance on one side corresponds to adepression on the other.

5 Claims, 6 Drawing Figures PATENTl-imun 4x914" v 38141208 sum 1 0P3PATEN'IEBM 4 m4 sum 3 0f 3 FIG. 5

1 SOUND-ABSORBING PANEL FOR AIRCONDITIONING DUCTS AND THE LIKESPECIFICATION Our present invention relates to a perforated panel ofsound-absorbing character adapted to be used as part of a wall of a ductor plenum chamber serving for the circulation of heating or cooling airin, for example, an air-conditioning system of the trickle type in whichthe air stream is cooled by the evaporation of dispersed water.

In such a system the air may pass, under the pressure of a circulatingpump, between a solid upper wall and a lower wall forming a falseceiling for a room to be cooled. The latter wall is advantageouslycomposed of one or more perforated panels permitting some of the airunder pressure to mix with the adjoining air volume. The peforations mayalso have a noise-absorbing function by breaking up acoustic wavefrontsso as to dissipate some of the energy of the sound waves.

The general object of our invention is to provide a panel designed tofacilitate a substantially uniform exchange of air or other fluids overa large area separating two spaces such as a plenum chamber or duct fora circulating air stream and a room to be cooled or heated thereby.

A more particular object is to provide a panel of this description whichis of .a highly sound-damping character so as to minimize the noiseresulting from this fluid flow.

These objects are realized, in accordance with the present invention, bythe provision of a body of sheet material which is bent alternately inopposite directions to form spaced-apart hollow projections or nozzleson each side separated by intervening depressions which are essentially(except for the distortion due to wall thickness) the negativecounterparts of the projections, each projection being provided at itspeak with one or more apertures which thus also lie at the bottom of adepression as seen from the opposite side of the panel.

With the projections converging outwardly toward The invention will bedescribed in greater detail hereinafter with reference to theaccompanying drawing in which:

FIG. 1 is a plan view of a panel embodying the invention;

FIG. 2 is a cross-sectional view taken on the line I l II of FIG. 1;

FIG. 3 is a fragmentary perspective view of another panel according tothe invention;

FIG. 4 is a view similar to FIG. 3, showing a modification;

FIG. 5 is a view similar to FIG. 1, illustrating a further embodiment;and

FIG. 6 is a cross-sectional view taken on the line VI VI of FIG. 5.

In FIGS. 1 and 2 we have shown a panel 1 of sheet material (e.g. foamplastic such as polystyrene) which is alternately bent in oppositedirections to create upper and lower protuberances or projections 3, 5in the form of funnel-shaped bosses provided with central apertures orports 2 and 4, respectively. As will be apparent from FIG: 1, the lowerapertures4 lie at the centers of squares defined by the upper apertures2, and vice versa. The two sides Aand B of the panel are assumed toadjoin a high-pressure and a low-pressure region, respectively: thesetwo sides are identically shaped except for a relative offset of thearrays of nozzles constituted by bosses 3 and 5. The upper and lowernozzles are aligned along the diagonals of the squares and, in thecross-sectional view of FIG. 2 taken along one such diagonal, are shownto be interconnected by smoothly'curved transition zones in the form ofgenerally S-shaped imperforate wall portions whose middle portionsextend within a median plane.

The perforated projections or nozzles 3, 5 act as acoustic resonatorshaving throats formed by the upper ports 2 and cavities constituted byadjoining air spaces.

their apertures, the air or other fluid moving along one side of thepanel is gently deflected away from the proximal apertures, traversingthem at a relatively reduced rate, but can pass more readily through thedistal apertures after expanding into the depressions leading thereto.Given a certain inherent resiliency of the sheet material, theimpingement of the fluid stream upon the curved, generally S-shapedboundaries of the alternating convexities and concavities is absorbedwith little or no noise generation. These boundaries of generally S-shape'd cross-section progressively approach each other across theentire width of the panel and constitute smoothly curved transitionzones between the two sets of projections on opposite sides of the panelbody.

The projections may be funnel-shaped or campaniform bosses or elongateribs extending over all or partof the panel. In either case they may beuniformly distributed over one side in an array symmetrically interleaved with the projections of a similar array on the opposite side.Thus, for example, the bosses on one side could be disposed at thecorners of identical squares whose centers are occupied by bossesprojecting from the opposite side. Such squares may also be defined byintersecting ribs on either side.

. cally like a sheet with two sets of perforations of differ- By virtueof their outwardly, i.e., downwardly converging shape, the lower bosses5 intercept a major part of the wavefront of an acoustic wave which istherefore accelerated on its passage through the constricted necks 4 andattenuated by the frictional resistance of the fluid layers merging inthat constriction. This results in a substantial increase in thenoise-absorbing capacity of the panel material. Moreover, owing to thedifferent flow rates through ports 2 and 4 as symbolized by the arrowsin FIG. 2, the panel 1 behaves acoustient diameters.

In FIG. 3 we have shown a modified panel 1' whose nozzles are formed byparallel ribs 3 and 5 projecting from the opposite sheet surfaces, theribs being provided with respective rows of perforations 2' and 4'.Again, one set of projections, e.g., the upper ribs 3' may confront aplenum chamber whereas the other set, 5', faces a room to be heated orcooled. The aerodynamic and acoustic behavior of this panel is similarto that of the panel shown in FIGS. 1 and 2. Here, too, the body of thesheet is of generally S-shaped cross-section between alternating upperand lower projections.

FIG. 4 shows a generally similar panel 1" differing from panel 1' onlyby the fact that the apertures of its ribs 3" and 5" are in the form oflongitudinally extending slots 2" and 4" in lieu of round holes 2' and4'.

In FIGS. 5 and 6 we have shown a further panel 1 whose projections 3"and 5" are in the shape of orthogonally intersecting rib segmentsprovided with similarly intersecting slots 2" and 4", respectively. Itwill be noted that the pattern of the points of intersection of theseslots is basically the same as that of the ports 2 and 4 of FIG. 1.Owing to the symmetry of its patterns, each of the panels 1, 1', etc.can be reversed without materially affecting the mode of operation.

Naturally, the shape of the apertures could differ from thoseillustrated, as by being elliptical, ovoid or polygonal. The widths ofthe apertures as well as their number depends, of course, upon the flowrate on the high-pressure side and the amount of fluid to be transferredto the low-pressure region. The regular distribution of these apertures,at the requisite density, insures a uniform spread of the cross-flowover the entire perforated area.

The constricted nozzle shape of the apertured projections lets theindividual fluid jets issue at relatively low pressure with avoidance ofturbulence which would tend to break up the fluid streams almost as soonas they leave the nozzles. Thus, the disclosed structure lets the jetspenetrate well into the adjoining region to mingle with its atmosphere.

The panels described and illustrated may be molded directly to shape orcould be deformed, under heat and pressure, from flat sheets ofthermoplastic material.

We claim:

l. A panel for partly confining a fluid stream, comprising a body ofsheet material bent alternately in opposite directions with formation oftwo mutually interleaved but substantially identical sets of projectionson opposite sides of said body and with apertures at the peaks of saidprojections, said projections converging outwardly toward saidapertures, the projections on one side forming depressions on the otherside which are substantially the negative counterparts of saidprojections adjacent projections on opposite sides of said body beinginter-connected by smoothly curved transition zones of generallyS-shaped cross-section with middle portions extending within a commonmedian plane of said body, said projections being at least one set ofparallel ribs on each side.

2. A panel as defined in claim 1 wherein said apertures are slotsextending longitudinally of said ribs.

3. A panel as defined in claim 1 wherein the ribs on each side areequispaced and symmetrically interleaved with the ribs on the respectiveopposite side.

4. A panel as defined in claim 1 wherein said transi tion zones areimperforate.

5. A panel for partly confining a fluid stream, comprising a body ofsheet material bent alternately in opposite directions with formation oftwo mutually interleaved but substantially identical sets of projectionsin the form of pairs of longitudinally slotted rib segments on oppositesides of said body, said rib segments converging outwardly toward theirlongitudinal slots, the rib segments on one side forming depressions onthe other side which are substantially the negative counterparts of saidrib segments, adjacent rib segments on 0pposite sides of said body beinginterconnected by smoothly curved transition zones of generally S-shapedcross-section with middle portions extending within a common medianplane of said body.

1. A panel for partly confining a fluid stream, comprising a body ofsheet material bent alternately in opposite directions with formation oftwo mutually interleaved but substantially identical sets of projectionson opposite sides of said body and with apertures at the peaks of saidprojections, said projections converging outwardly toward saidapertures, the projections on one side forming depressions on the otherside which are substantially the negative counterparts of saidprojections adjacent projections on opposite sides of said body beinginterconnected by smoothly curved transition zones of generally Sshapedcross-section with middle portions extending within a common medianplane of said body, said projections being at least one set of parallelribs on each side.
 2. A panel as defined in claim 1 wherein saidapertures are slots extending longitudinally of said ribs.
 3. A panel asdefined in claim 1 wherein the ribs on each side are equispaced andsymmetrically interleaved with the ribs on the respective opposite side.4. A panel as defined in claim 1 wherein said transition zones areimperforate.
 5. A panel for partly confining a fluid stream, comprisinga body of sheet material bent alternately in opposite directions withformation of two mutually interleaved but substantially identical setsof projections in the form of pairs of longitudinally slotted ribsegments on opposite sides of said body, said rib segments convergingoutwardly toward their longitudinal slots, the rib segments on one sideforming depressions on the other side which are substantially thenegative counterparts of said rib segments, adjacent rib segments onopposite sides of said body being interconnected by smoothly curvedtransition zones of generally S-shaped cross-section with middleportions extending within a common median plane of said body.